The electronic Signature does not need activation. You can use it directly from your Resources>eContracts page as soon as you open a Clustdoc account.

You can use the electronic Signature (unlimited signatures allowed) during your trial and also after you've activated your Clustdoc plan.

The difference between electronic and digital signatures

Digital signatures are seen as an equivalent of notarized signatures and require a confirmation from a third-party (The Certificate).
Most of the time digital and electronic situations are legally binding. You may want to check if your federal legislation has strict requirements related to this. 

Type of esignature solutions available with Clustdoc

Clustdoc offers both solutions: electronic and digital eSignatures. 

The electronic Signature is unlimited. 

You can activate the digital eSignature in he Booster section. Click on your Picture>Set up this team>Boosters and activate the Certified eSignature.
The electronic signature doesn't need activation, you can just set up your e-contract, add fields and signature placeholders, import the e-contract in your process and get your documents signed.